Report from the Planetary Defense 2015 Conference. One of the highlights of the PDC in Frascati was the multi-part simulation of an impact stretching over 7 years of time (but only 5 days at the conference). The best description I have seen of this exercise is from Oliver Morton published in the Economist special section on alternative futures. It reads in part:
If an asteroid heads for Earth: Taking the hit
ON APRIL 13th 2015 the Minor Planet Centre (MPC), an office with a staff of six which looks after such matters for the International Astronomical Union, recorded hundreds of newly discovered asteroids—a typical daily haul. The one to which it assigned the name 2015 PDC, though, stood out. The calculations for 2015 PDC showed that on September 3rd 2022 the Earth would cross the corridor where the asteroid might be. The two might collide.
As 2015 PDC’s orbit became better known the corridor in which it might be on that fateful day in 2022 shortened. But it still contained the Earth. By June the probability of an impact had risen to 1%, making it the most threatening asteroid astronomers had ever seen. By September governments in America, Europe, Russia and China had started work on space missions aimed at changing the asteroid’s orbit by ramming into it. Even at a speed of more than 10km a second, hitting a billion-tonne asteroid with a few tonnes of spacecraft will make only a minute difference to the asteroid’s orbit. But a minute difference, made early enough, can provide the margin between a near miss and a hit that is palpable on a planetary scale. And 2015 PDC looked like providing such a hit….
Towards the end of 2015 the sun came between the Earth and the rock, making further observations impossible for a while. After observations resumed the following year, though, an impact became certain. The remaining uncertainty was about where, exactly, it would hit. The risk corridor was wrapped around the Earth on a great-circle arc that began in the tropical Pacific and ran north-west over the Philippines and across the South China Sea before passing over a swathe of Asia beginning in Vietnam and ending in Iran. The track passed over a surprisingly large fraction of the world’s population and three megacities—Dhaka, New Delhi and Tehran. You would have been hard put to have imagined a more threatening rock…..
That was because Paul Chodas, an asteroid expert at JPL, the laboratory that manages most of NASA’s planetary science, had put a lot of his own imagination into making 2015 PDC intriguingly disturbing. He and a few colleagues invented the asteroid, and its orbit, as a scenario to be discussed at the Planetary Defence Conference held in Frascati this April. The scenario unfolded over five days, in breaks between technical papers, with participants drafted in to imagine the reactions of world leaders, the media and the public. Their deliberations revealed a lot about the nature of the threat asteroids pose and the response that a real threat might provoke—a response which could make the danger greater than it would otherwise be.
In Dr Chodas’s scenario the deflection went wrong. Instead of being nudged safely onto a new trajectory, the asteroid was cleft in two. The larger part had been given a big enough impulse to no longer be an imminent threat, but the smaller part was still on a collision course. And now its orbit was newly uncertain. The corridor that had been shortening was lengthened, with the once-threatened, then-safe places between Vietnam and Tehran newly at risk again thanks to the actions of space programmes that were mostly based in places (Europe, America, Russia) that were at no direct risk at all. India began work on a mission that would use a nuclear warhead to try to blast the new fragment to smithereens on its final approach—but which might have simply changed its impact point again.
China warned that it wanted a veto over any such mission; if it did not approve of the way it was being done it would feel justified in using anti-satellite weapons to shoot down the Indian rocket pretty much as soon as it took off. Iran, previously safe, fulminated against the Great Satan, and it was hard not to think it had a point. Hannes Mayer, an Austrian lawyer who has given the application of space law to such situations a lot of thought, raised the possibility that by altering the asteroid’s orbit the intercepting nations changed its legal status from that of a “celestial body” for which no one was responsible to that of a “space object”—and thus become liable for any damage that it did.
By the end of the scenario, when the asteroid was a few days from exploding in the sky over Dhaka with more power than 1,000 Hiroshima bombs and more than 20m people were being evacuated, that was looking like a great deal of liability. The question of India’s last-ditch nuclear interception, and China’s worries, were brushed aside as beyond the scenario’s scope. In the real world, though, a botched interception which created a crisis for people who would otherwise have avoided one would be a grave issue—perhaps, in some circumstances, casus belli….
To read the full story, including the ending, go to [http://worldif.economist.com/article/12/what-if-an-asteroid-heads-for-earth-taking-the-hit#null]
End-of-the-World Scenario for This Week:
While scientists are concerned about real asteroids and possible real future impact possibilities, a part of the public lives in an alternate fantasy world. For months the story has circulated, aided by the tabloid press and internet bloggers, that a 2 km asteroid would strike the Earth in Puerto Rico in the last week of September. This rumor made no pretense that it was based on any observations of any NEO; rather it was a vision of a self-appointed seer.
Scientists, if they knew about this story, dismissed it as obvious nonsense. But it received so much publicity that NASA decided to issue a press release pointing out that it was nonsense. Predictably, the ensuing press coverage greatly increased. Here are thred samples from the weird world of the on-line tabloids.
Nasa Rubbishes Claims Asteroid Will Destroy Earth in Four Weeks as It Won’t Even Hit Us. (Aug 28)
Conspiracy theorists have claimed the world will be destroyed upon an asteroids arrival between September 21 and 28.
Not so, say Nasa. Paul Chodas, from Nasa’s Near-Earth Object office, has thrown out the claims. Speaking at its Jet Propulsion Laboratory, in Pasadena, California, he said: “There is no existing evidence that an asteroid or any other celestial object is on a trajectory that will impact Earth. “In fact, not a single one of the known objects has any credible chance of hitting our planet over the next century. “There is no scientific basis, not one shred of evidence, that an asteroid or any other celestial object will impact Earth on those dates.”
The origins of the claim come from self-proclaimed prophet Efrain Rodriguez, who has passed his research onto Nasa. He says he had a vision of the asteroid “entering the airspace of the town of Arecibo in Puerto Rico, striking the sea between the island of Mona and Mayaguez and triggering a magnitude 12 earthquake”. Because the prophecy has so many people worried, Nasa has been forced to issue a statement clarifying matters.
Will the World End on September 28? Blood Moon and Asteroid Impact are Heralds of Apocalypse. (Sept 14)
Conspiracy theorists are predicting a cataclysmic event which will destroy civilisation – because of the looming blood moon and a prophesied meteor strike. End-of-time cranks on various blogs and websites have come up with the period between September 22-28 as the likely time frame for the impending catastrophe. On September 28th we will see the moon turn an incredible blood colour – and some think the end of days will arrive with it.
Asteroid Apocalypse 2015: Did Top Asteroid Expert Just Say Doomsday is on the Way After All? (Sept 16)
NASA in August took the unusual step of publicly debunking the online asteroid apocalypse rumors that had circulated throughout 2015, assuring the public that there existed “not one shred of evidence” that a major asteroid strike would occur in September of this year, as internet conspiracy theories claimed.
One version of the asteroid apocalypse rumor held that the massive impact — capable of disrupting or even wiping out all life in Earth — would take place on September 15. That date has now come and gone. But other versions of the story — many of which also alleged a NASA cover-up of the imminent doomsday strike — gave September 24 or September 28 as possible dates for the world-ending asteroid impact.
“If there were any object large enough to do that type of destruction in September, we would have seen something of it by now,” said Paul Chodas, manager of the NASA Near-Earth Object Office, back in August, as the space agency attempted to calm fears of the allegedly impeding asteroid strike.
But not so fast, says a British astronomy expert — Professor Robert Walsh of the University of Central Lancashire in England. There’s still a chance of a huge asteroid disaster, and humanity would be ill-advised, Walsh says, to treat the threat lightly. “What you may not realize is that Earth is hit with about a hundred tons of extraterrestrial material every day,” Walsh told Britain’s Daily Mirror newspaper on Wednesday. “Earth has experienced very destructive impacts in the past. Just ask any dinosaur.”….
NEO News (now in its twentieth year of distribution) is an informal compilation of news and opinion dealing with Near Earth Objects (NEOs) and their impacts. These opinions are the responsibility of the individual authors and do not represent the positions of NASA, Ames Research Center, the International Astronomical Union, or any other organization. If anyone wishes to copy or redistribute original material from these notes, fully or in part, please include this disclaimer.